Expression of the c-Ha-ras and c-mye genes in aflatoxin B₁-induced hepatocellular carcinomas

Expression and activation of several c-oncogenes in seven hepatocellular carcinomas from seven separate rats treated with aflatoxin B₁ (AFB₁) were examined by Northern and Southern blot analyses. Both c-Ha-ras and c-myc transcripts were elevated at high levels in all hepatomas. Moreover, in one of them, T2-1 hepatoma, the c-myc gene was amplified only in a tumor part of liver without significant rearrangement. N-ras specific transcripts were not elevated in these hepatomas. The present data suggest that the consistently increased expression or deregulation of the c-myc and c-Ha-ras genes may play an important role in the development of hepatomas induced by AFB₁.